The present invention relates to a signature transfer device for transferring signatures as cut off and folded to a discharge position in a folder for a rotary printing press.
Web-fed rotary printing presses have a folder for cutting off and folding a web which has been printed. The folder includes a signature transfer device including upper and lower tapes for transferring therebetween a signature fed from the folder, a plurality of front lays for stopping the signature, and a chopper blade for folding the signature as stopped by the front lays. Proper folding on the chopper blade requires that a leading end of the signature extends perpendicularly to the chopper blade. However, the tapes in the prior signature transfer device cannot be maintained under constant tension, and hence some tapes are liable to slip on the signature, causing the latter to be displaced at localized areas and inclined relative to the chopper blade. The tension imposed on the tapes adjacent to the front lays tends to be increased so that the signature will forcibly be pressed against the front lays, resulting in wrinkles on the leading edge of the signature. Therefore, it has been difficult for the conventional signature transfer device to gain desired perpendicularity of the signature relative to the chopper blade, and hence to fold a signature on itself with a required accuracy.